• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.369-375
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• 2004

Gas turbine engine simulation in terms of transient, steady state performance and operational characteristics is complex work at the various engineering functions of aero engine manufacturers. Especially, efficiency of control system design and development in terms of cost, development period and technical relevance implies controlling diverse simulation and identification activities. The previous engine simulation has been accomplished within a limited analysis area such as fan, compressor, combustor, turbine, controller, etc. and this has resulted in improper engine performance and control characteristics because of limited interaction between analysis areas. In this paper, we propose a new simulation methodology for gas turbine engine performance analysis as well as its digital controller to solve difficulties as mentioned above. The novel method has particularities of (ⅰ) resulting in the integrated control simulation using almost every component/module analysis, (ⅱ) providing automated math model generation process of engine itself, various engine subsystems and control compensators/regulators, (ⅲ) presenting total sophisticated output results and easy understandable graphic display for a final user. We call this simulation system GT3GS (Gas Turbine 3D Graphic Simulator). GT3GS was built on both software and hardware technology for total simulation capable of high calculation flexibility as well as interface with real engine controller. All components in the simulator were implemented using COTS (Commercial Off the Shelf) modules. In addition, described here includes GT3GS main features and future works for better gas turbine engine simulation.

• Journal of the Korean Society of Propulsion Engineers
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• v.27 no.1
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• pp.37-48
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• 2023

In this study, performance analysis modeling of two spool mixed flow type turbofan engine according to steady-state and transient is performed. The target engine is selected as F100-PW-229 from Pratt & Whitney, and main engine components including fan, high pressure compressors, combustion, high pressure turbines, low pressure turbines, mixer, convergent-divergent nozzle are modeled. The cooling effect of turbine through secondary flow path are considered in engine simulation model. We develop in-house Matlab/Simulink-based engine performance analysis program capable of analyzing internal engine state and compare it with GASTURB which is generally used as a commercial engine analysis program.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.425-432
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• 2009

The construction industry has been a main pillar and serves as a regulator of the Hong Kong economy. Subsequently, the fluctuations in the level of construction output can induce significant rippling effects to the economy. The Asian Financial Crisis started in 1997 and the SARS outbreak in 2003 both introduced major challenges and impacts to the Hong Kong economy and consequently the construction sector. Such decline in the importance of construction has suggested a possible structural change in the sector. It is worth investigating the driving forces behind the construction demand and see if they have changed after the heavy impacts in the past decade. The above considerations have, therefore, been the motivation of the present study to model the Hong Kong residential construction demand through multiple regression technique which can identify the significant influencing factors to the residential demand. The residential construction is studied as it constitutes a significant portion of the total construction volume. The residential sector has great influence to the general economy of Hong Kong. It is found that the underlying market structure and the driving factors for Hong Kong residential demand before and after the Asian Economic Crisis and SARS outbreak are different, suggesting that the residential construction sector or even the larger construction industry may have undergone a major structural change as Hong Kong's economy approaches maturity. It is also observed that the past literatures on construction demand are mostly focusing on predicting demand under a stable economic environment. Hence, it is worth examining if it is possible to model during economic hardship when the residential sector fluctuate dramatically under different external impacts, such as the recent global financial tsunami.

• Asia Marketing Journal
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• v.17 no.4
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• pp.63-88
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• 2016

K-Pop is hugely promoted offline/online in East Asia, while efforts to promote it elsewhere are kept to a minimum. Whilst addressing the role of digital marketing in the promotion of K-Pop in the Brazilian music industry this study aims to demonstrate that K-pop will provide its audience with a unique and engaging experience if it thinks globally and acts locally in its marketing and communication strategies. A survey of K-Pop's world fan base was carried out online with 1,074 fans to determine the validity of the hypothesis. The results have demonstrated the need to adapt global and intercultural strategies to local markets with increasing brand awareness through utilizing digital marketing. For example, to increase K-Pop's popularity and market share in Brazil, it is not required to sing in Brazilian Portuguese, contrary to what might be perceived but fully singing in English would help breaking into the market dominated by domestic music as songs would have a higher probability to be included in the international soundtrack of a Brazilian telenovela and promote the K-Pop artist not only across Brazil but also give the artist exposure in all the markets the Brazilian telenovela is exported to, opening an entry door to those markets. K-Pop audience segmentation and psychographic profiling is crucial to the understanding of each market's consumer's preferences, likes, dislikes and their buying habits as it was proven through Brazil's digital media, social media, digital music market and K-Pop market analysis within the global context of the study. It should be also considered that brand extensions are not standard everywhere and that there are cultures where different product categories are not directly associated with its main corporate owner which requires extensive local market knowledge to succeed. The primary and secondary data research that we conducted for this study intended to demonstrate that K-Pop can be successful in Brazil and in Latin America and increase their local and regional market share if digital marketing and communication strategies are tailored to each individual market.

• Nuclear Engineering and Technology
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• v.55 no.7
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• pp.2628-2641
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• 2023

Nuclear safety is the lifeline for the development and application of nuclear energy. In severe accidents of pressurized water reactor (PWR), aerosols, as the main carrier of fission products, are suspended in the containment vessel, posing a potential threat of radioactive contamination caused by leakage into the environment. The gas-phase aerosols suspended in the containment will settle onto the wall or sump water through the natural deposition mechanism, thereby reducing atmospheric radioactivity. Aiming at the low accuracy of the aerosol model in the ISAA code, this paper improves the natural deposition model of aerosol in the containment. The aerosol dynamic shape factor was introduced to correct the natural deposition rate of non-spherical aerosols. Moreover, the gravity, Brownian diffusion, thermophoresis and diffusiophoresis deposition models were improved. In addition, ABCOVE, AHMED and LACE experiments were selected to validate and evaluate the improved ISAA code. According to the calculation results, the improved model can more accurately simulate the peak aerosol mass and respond to the influence of the containment pressure and temperature on the natural deposition rate of aerosols. At the same time, it can significantly improve the calculation accuracy of the residual mass of aerosols in the containment. The performance of improved ISAA can meet the requirements for analyzing the natural deposition behavior of aerosol in containment of advanced PWRs in severe accident. In the future, further optimization will be made to address the problems found in the current aerosol model.

• Earthquakes and Structures
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• v.26 no.1
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• pp.31-48
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• 2024

In order to get a better understanding of seismic performance of exterior beam-column joint, reciprocating loading tests with variable loading speeds or axial forces were carried out. The main findings indicate that only few cracks exist on the surface of the joint core area, while the plastic hinge region at the beam end is seriously damaged. The damage of the specimen is more serious with the increase of the upper limit of variable axial force. The deflection ductility coefficient of specimen decreases to various degrees after the upper limit of variable axial force increases. In addition, the higher the loading speed is, the lower the deflection ductility coefficient of the specimen is. The stiffness of the specimen decreases as the upper limit of variable axial force or the loading speed increase. Compared to the influence of variable axial force, the influence of the loading speed on the stiffness degradation of the specimen is more obvious. The cumulative energy dissipation and the equivalent viscous damping coefficient of specimen decrease with the increase of loading speed. The influence of variable axial force on the energy dissipation of specimen varies under different loading speeds. Based on the truss model, the biaxial stress criterion, the Rankine criterion, the Kent-Scott-Park model, the equivalent theorem of shearing stress, the softened strut-and-tie model, the controlled slip theory and the proposed equations, a calculation method for the shear capacity is proposed with satisfactory prediction results.

• Informatization Policy
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• v.31 no.3
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• pp.72-87
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• 2024

The recent COVID-19 pandemic has witnessed the rapid growth of the fitness app market, with weight management apps occupying a substantial market segment. In connection, a growing body of research has been conducted to examine design elements aimed at fostering user motivation and long-term engagement, without considering user characteristics, which are critical to understanding user responses to weight-loss apps. Therefore, to fill this research gap, this research focuses on the weight stigma of users and strives to examine what affects such user characteristics have on the weight-loss apps. The main findings of this study is that higher help-seeking intention and willingness to use weight management apps among those who show high weight stigma consciousness than those with low consciousness. This study further shows the interaction effects between weight stigma consciousness AI types of service. This research provides new insights on how to design elements of weight-loss apps targeting both non-stigmatized and stigmatized users. It shows that in designing public applications, feeling-based AI that considers the psychological needs of users may be more effective for individuals with weight stigma.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.1
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• pp.57-63
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• 2017

Objective: Two experiments were conducted to determine the effects of adding exogenous phytase and xylanase, individually or in combination, as well as pelleting on nutrient digestibility, available energy content of wheat and the performance of growing pigs fed wheat-based diets. Methods: In Experiment 1, forty-eight barrows with an initial body weight of $35.9{\pm}0.6kg$ were randomly assigned to a $2{\times}4$ factorial experiment with the main effects being feed form (pellet vs meal) and enzyme supplementation (none, 10,000 U/kg phytase, 4,000 U/kg xylanase or 10,000 U/kg phytase plus 4,000 U/kg xylanase). The basal diet contained 97.8% wheat. Pigs were placed in metabolic cages for a 7-d adaptation period followed by a 5-d total collection of feces and urine. Nutrient digestibility and available energy content were determined. Experiment 2 was conducted to evaluate the effects of pelleting and enzymes on performance of wheat for growing pigs. In this experiment, 180 growing pigs ($35.2{\pm}9.0kg\;BW$) were allocated to 1 of 6 treatments according to a $2{\times}3$ factorial treatment arrangement with the main effects being feed form (meal vs pellet) and enzyme supplementation (0, 2,500 or 5,000 U/kg xylanase). Results: In Experiment 1, there were no interactions between feed form and enzyme supplementation. Pelleting reduced the digestibility of acid detergent fiber (ADF) by 6.4 percentage units (p<0.01), increased the digestibility of energy by 0.6 percentage units (p<0.05), and tended to improve the digestibility of crude protein by 0.5 percentage units (p = 0.07) compared with diets in mash form. The addition of phytase improved the digestibility of phosphorus (p<0.01) and calcium (p<0.01) by 6.9 and 7.6 percentage units respectively compared with control group. Adding xylanase tended to increase the digestibility of crude protein by 1.0 percentage units (p = 0.09) and increased the digestibility of neutral detergent fiber (NDF) (p<0.01) compared with control group. Supplementation of the xylanase-phytase combination improved the digestibility of phosphorus (p<0.01) but impaired NDF digestibility (p<0.05) compared with adding xylanase alone. In Experiment 2, adding xylanase increased average daily gain (p<0.01) and linearly improved the feed:gain ratio (p<0.01) compared with control group. Conclusion: Pelleting improved energy digestibility but decreased ADF digestibility. Adding xylanase increased crude protein digestibility and pig performance. Phytase increased the apparent total tract digestibility of phosphorus and calcium. The combination of phytase-xylanase supplementation impaired the effects of xylanase on NDF digestibility.

• Korean journal of food and cookery science
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• v.28 no.5
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• pp.629-639
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• 2012

Jeon refers to a type of Korean cuisine used as a side dish, made with various ingredients such as meat, vegetables, or fish, mixed with flour batter and coated with egg batter and then pan-fried on both sides with oil so that heat spreads through them well. The aim of this study was to provide a cornerstone of further research on Korean dietary life, by reviewing types, recipes and names of Jeon recorded in ancient cookbooks (Korean literatures) and by analyzing changes in recipes to make Jeon, which our ancestors used wisely as one type of side dish. Considering developments and changes recorded in old documents, the Jeon recipe appeared relatively later than the recipes for grilling, steaming et al, which had been developed much earlier, and it had not been recorded until the 1600s. Changes of Jeon recipes by time period are as follows. In the 1600s, there were three recipes: frying only with grain batter after preparation of ingredients, frying right after preparation of ingredients, and putting ingredients on already fried watery batter. These three recipes were still used in the 1700s, in addition to a new recipe, in which ingredients were oil-fried to be skewered. Today's recipe in which prepared ingredients are fried after getting coated with flour and egg only appeared in 1800s. This has been the main recipe for Jeon ever since. In that time period, there was more variety of recipes and ingredients than before. For instance, Jeon was used for soup or steamed dishes instead of being served as a dish itself. Buchimgae with mixed ingredients was also considered Jeon. In the 1900s, there appeared more names for Jeon as more sorts of ingredients got used, even though there were no new recipes for Jeon. The above-mentioned historical records show that traditional recipes for Jeon have been applied to various dishes, using diverse ingredients, and it might be a smart solution to today's problematic dietary habits involving excessive intake of nutrients, in that it provides a healthy way to add fat. In the same sense, the recipe for Jeon can play an active role in internationalization of Korean foods, in which healthiness is a main feature. According to ancient documents, the recipes for Jeon were used even for meals that were not side dishes, such as Jun-Gwa (Jung-Gwa), Jun-Yak and fried rice-cake. Also, there were dishes using the same recipes even without carrying the name of Jeon, like Buchim or Jijim. This might be worthy of further examination in culinary science.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.6
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• pp.8-14
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• 2017

Gearboxes for power transmission of a rotorcraft transfer power generated by an engine to the fan and the pusher for up, down and forward flight. The gearboxes are divided into the main gearbox and the sub-gearbox. The main goal of the gearbox design is to design the weight as light as possible within a range that satisfies all given requirements (transmission power, mounting space, etc.). In particular, the initial conceptual design is very important to reduce the weight of the gearbox, since the weight can vary greatly depending on the system configuration, even if it has the same function. In this study, various conceptual designs of the gearbox according to the installation position of the engine were presented. Also, the element parts such as gears and bearings in each concept design were designed by sizing for their life, and the estimated weights of the conceptual system configuration were compared.